1. Technical Field
The invention relates to a pallet-stacking device which maximizes the vertical stacking capability of adjacent pairs of loaded pallets.
2. Background Information
Bottle-carrying crates or xe2x80x9ccarriersxe2x80x9d are typically stacked in vertical sets on top of pallets to create three-dimensional xe2x80x9ccontainer arrays.xe2x80x9d For example, bottle carriers filled with blow-molded plastic bottles are often stacked in perhaps three to seven layers atop a given pallet. Such bottle carriers typically define bottle seats in an upper surface within which to receive the base portion of each bottle, and recesses in a lower surface within which to receive the tops of the bottles carried in the next-lower bottle carrier. Alternatively, cardboard or molded-plastic tier sheets are often used to separate each bottle carrier layer. Such a pallet loaded with stacked bottle carriers is conveniently handled by a forklift for shipment or storage.
Because vertical space in a warehouse is significantly less expensive than floor space, it is desirable to stack fully-loaded pallets vertically as high as possible. However, various problems arise in stacking loaded pallets directly on top of other fully loaded pallets, including those associated with the possible uneven loading of the top layer of exposed container tops by the three horizontally-spaced slats that typically define the bottom surface of a wooden pallet; and the resulting stack of pallets frequently lacks the desired stability.
Under one prior art approach to increase the stacking capacity of fully-loaded pallets, as taught in U.S. Pat. No. 5,016,761 to Stoddard et al., a xe2x80x9ctop cap memberxe2x80x9d is secured on top of the loaded pallet to provide a stable supporting surface for another pallet. The top cap member is formed from a monolithic plastic sheet of uniform thickness that is deformed to provide raised lands on its upper surface and corresponding dimples on its lower surface (the dimples being positioned to receive the tops of containers forming the uppermost layer of the loaded pallet). The presence of the underside dimples makes sliding the top cap member laterally across the uppermost layer of container tops more difficult when preparing the loaded pallet for stacked storage or display.
According to another prior art approach, as taught in U.S. Pat. No. 5,894,804, a two-ply, pliable separator sheet is used to separate the layered pallets. The upper surface includes raised nubs while the lower surface includes corresponding concavities. Because the sheet is pliable, the nubs that engage the underside of the upper pallet collapse under its weight to thereby ensure that the pallet""s load is not borne exclusively by the nubs. The separator sheet""s other, noncollapsed nubs form a xe2x80x9craised barrierxe2x80x9d resisting sliding movement of the upper pallet relative to the lower pallet. The lower ply material is also said to have a relatively greater coefficient of friction than that of the upper ply material, to thereby allow the lower surface to xe2x80x9cgripxe2x80x9d the cargo loaded on the lower pallet. Unfortunately, the pliable aspect of such separator sheets makes handling and storage of such sheets more difficult, while the xe2x80x9cgrippyxe2x80x9d lower ply makes it more difficult to slide the sheet across the top of the lower pallet prior to stacking the upper pallet on top of the sheet. Still further, the use of two materials necessarily increases the cost and complexity associated with production of such separator sheets. And, lastly, the pliable nature of such separator sheets limits the stability of the resulting pallet stack because the sheet can only serve to prevent splaying of the lower pallet""s cargo and does not otherwise serve to improve the quality of the surface upon which the upper pallet rests.
It is an object of the invention to provide a durable pallet-stacking device that is useful in optimizing the height to which loaded pallets can be vertically stacked.
It is also an object of the invention to provide a durable pallet-stacking device that improves the quality of the surface upon which an upper pallet of a stack of pallets rests.
Yet another object of the invention is to provide a pallet-stacking device that can be used to improve the stability of adjacent stacks of loaded pallets and, yet, can assume a more compact form for storage between uses.
Under the invention, an article or device for use in stacking adjacent pairs of pallets loaded, for example, with stacked container arrays includes a pair of interconnected sections. Each section of the device has a generally flat bottom surface adapted to rest on top of a respective loaded pallet, for example, the container tops of an uppermost layer of the container array. Each section of the device also has a top surface that includes a plurality of raised surface features on which to support another pallet, and a first edge including a plurality of hinge components from the group consisting of a first hinge component and a second hinge component. By way of example only, in an exemplary embodiment, the first and second hinge components respectively include a pivot pin and a pin grip that, preferably, are formed such that the two sections can be snapped together when one section is disposed at a predetermined angle, such as a 90xc2x0 angle, relative to the other section. In accordance with a feature of the invention, an uppermost portion of each raised surface feature of each section lies within a respective first reference plane, with the first reference plane being in a substantially parallel-spaced relation to the bottom surface; and the hinge components of the sections cooperate to interconnect the sections for relative pivoting movement about a pivot axis that lies beneath the respective first reference plane of each section.
Most preferably, the surface features of the top surface include a plurality of raised portions or lands separated by a plurality of lowered portions or valleys. In an exemplary embodiment, the raised portions extend in a direction generally perpendicular to the pivot axis, with the resulting parallel-spaced raised lands extending substantially across a longitudinal dimension of the section. In accordance with another feature of the invention, the surface features of the first section are preferably complementary to the surface features of the second section, and the pivot axis preferably lies between the first reference plane defined by the raised lands and a second reference plane that intersects the lowermost portions of the valleys on the top surface of each section. In this manner, the raised portions of the first section oppose the lowered portions of the second section when the first section is pivoted on top of the second section, thereby providing the folded device with a compact form that is well suited for stacked storage. Most preferably, the first and second sections have a substantially identical shape to facilitate manufacture and lower the cost of the device using, for example, two identical, injection-molded plastic sections.
In accordance with yet another feature of the invention, the hinged edge of each section also includes one or more respective edge features that together cooperate to restrict relative pivoting movement of the first and second sections about the pivot axis, thereby improving device rigidity when opened. While the invention contemplates any suitable combinations of edge features for restricting such relative pivoting movement, an exemplary embodiment includes lateral features defined on the pin grips of one section that resiliently engage side surfaces defining the cut-out region of the other section adjacent to the pivot pin. The exemplary embodiment also includes cooperating edge features that define a detent, for example, a tongue and slot arrangement, for locking the first section relative to the second section about the pivot axis when the bottom surface of the first section is substantially coplanar with the bottom surface of the second section. The exemplary embodiment further includes cooperating edge features that abuttingly engage as the bottom surface of the first section is urged into a substantially coplanar relationship with the bottom surface of the second section.
In accordance with still another feature of the invention, each section of the device further includes a small lip extending along a second edge that is opposite the hinge, and that projects downwardly beneath the bottom surface of the section. The lip advantageously prevents longitudinal sliding movement of the device after the device is positioned atop and across a pair of adjacent loaded pallets, while the otherwise generally flat bottom surface of the device facilitates the lateral insertion, removal and alignment of the device atop and across the loaded pallets. The device further includes a plurality of handles that are integrally defined in each section, preferably along each longitudinal edge of the device. The handles further facilitate the lateral insertion and removal of the device and, when defined in each section such that the handles of the first section are generally aligned with the handles of the second section when the first section is pivoted on top of the second section, the handles conveniently facilitate handling of the folded device.